This invention relates to pharmaceutical preparations for oral administration encapsulated in a capsule dosage form and more particularly relates to such therapeutic preparations comprising coated pellets or spheroids which release a dose of an active medicinal substance at different times in the digestive system of a patient.
Timed disintegration capsules for the sequential, timed release of medicinal substances into a patient's system are known in the art. Generally such capsules or tablets consist of particles containing the medicinal substance to be introduced into the system, and a coating over the particles of a material which is resistant to disintegration for a selected period of time. Such coating compositions are also referred to as enteric coating compositions, that is, compositions which are generally resistant to disintegration in the stomach, but which disintegrate in the intestine. Enteric compositions also include compositions which disintegrate slowly in the stomach such that the medicinal substance is not released until the capsule or tablet has reached the intestine of the patient. For example, coatings comprising bees wax and glyceryl monostearate; bees wax, shellac and cellulose; and cetyl alcohol, mastic and shellac have been proposed for use as slow release or timed release coatings for medicinal substances. Release of the medicinal substance by disintegration of the coating is generally controlled by varying the thickness of the coating or by altering its composition.
U.S. Pat. No. 2,809,918 discloses inert drug coated nonpareils which are enteric coated with a shellac-stearic acid mixture. U.S. Pat. No. 3,119,742 discloses coated drug crystals used as particulates for sustained release formulations. U.S. Pat. No. 2,921,883 discloses "Spansule," nonenteric coated spheroids designed for sustained release. U.S. Pat. No. 3,835,221 discloses oral delayed action "globules" coated with a mixture of polyvinylacetate and ethyl cellulose, useful as an "inert carrier core." F. W. Goodhart et al., Pharmaceutical Technology, page 64-71, Apr. 1984, discloses the evaluation of Eudragit E 30 D as an aqueous film forming dispersion for controlled release of phenylpropanolamine hydrochloride.
The prior art compositions have generally proved deficient in the case where the medicinal substance is extensively metabolized presystemically or has a relatively short elimination half-life resulting in sub-therapeutic plasma levels. Also, with many patients, the coatings are not disintegrated to the extent necessary to release the medicinal substance until the tablet or capsule has reached the colon and the medicinal substance is discharged from the system rather than absorbed by the intestine.
The present invention provided three repeated releases of a medicinal substance for once daily administration of those medicinal substances which are extensively metabolized presystemically or have relatively short elimination half-lives. This system results in superior oral bioavailability as compared to a continuous release system for a medicinal substance over a 6 to 24 hour period. The present invention also provides the convenience of not requiring the administration of divided doses during a 24 hour period and results in better patient compliance.
The medicinal agents useful in the invention are those that exhibit a significant presystemic metabolism or have a relatively short elimination half life that normally would be administered in divided dosess two or more times a day. Such medicinal agents include the cardiovascular drugs such as propanolol hydrochloride, isosorbide dinitrate, isosorbide-5-mononitrate, pelrinone (see U.S. Pat. No. 4,505,910), acifran (see U.S. Pat. No. 4,244,958) verapamil hydrochloride, quinidine sulfate, the cerebral activators such as vinpocetine, Ay-30109 (see U.S. Pat. application Ser. No. 811,551, filed Dec. 20, 1985 by Jirkovsky et al., entitled 6, 7, 8, 9-Tetrahydro-10-methylpyrido[1,2-a]indole-9-Amines and Derivatives Thereof (AHP-8728); the analgesics such as those disclosed and claimed in U.S. Pat. application Ser. No. 726,197, filed Apr. 22, 1985, the antihistamines such as chlorpheniramine and bromopheniramine; and the decongestants such as pseudoephedrine and phenylpropanolamine.
In the case of medicinal agents having a significant pH dependent solubility profile, weak organic acids such as citric, tartaric, fumaric and glutamic acids may be added to the spheroid formulation to facilitate drug dissolution throughout the gastrointestinal tract.
The present invention also lies in the general area of timed disintegration coatings and represents a substantial improvement over the prior art compositions in that the time of disintegration is readily controllable and easily adjusted for release of a medicinal substance.
The present invention relates to a therapeutic composition comprising a pharmaceutical gelatin capsule containing (i) a powder blend of a medicinal substance and two groups of spheroids each containing the medicinal substance or (ii) three groups of spheroids each containing a medicinal substance, the alternative group of spheroids comprising uncoated spheroids containing a loading dose of the medicinal substance. In each embodiment, the second group of spheroids comprises pH sensitive coated spheroids containing a second dose of the medicinal substnce and the third group of spheroids comprises double coated spheroids containing a third dose of the medicinal substance.
A further preferred aspect of the present invention relates to a therapeutic composition consisting of a pharmaceutical gelatin capsule containing three groups of spheroids wherein, (a) the first group of spheroids comprises an active medicinal substance admixed with non-water swellable microcrystalline cellulose, (b) the second group of spheroids comprises the medicinal substance in admisture with non-water swellable microcrystalline cellulose and is coated with a copolymer based on methacrylic acid and methacrylic acid methyl ester such as Eudragit S to the extent of 20% to 30% by weight of uncoated spheriods or polyvinyl acetate phthalate to the extent of 5% to 15% by weight of uncoated spheroids and preferably to the extent of 10% by weight and (c) the third group of spheroids comprises the medicinal substance in admixture with non-water swellable microcrystalline cellulose and is coated with (i) an undercoat to the extent of 2.5% to 5.5% by weight of uncoated spheroids selected from the group consisting of hydroxypropyl methylcellulose and hydroxypropyl methylcellulose containing as a disintegrant sodium carboxymethylcellulose, such as AcDiSol, or sodium starch glycolate such as Explotab, werein the AcDiSol is present to the extent of 10% to 60% by weight of the hydroxypropyl methylcellulose and the Explotab is present to the extent of 10% to 60% by weight of the hydroxypropyl methyl celulose and an (i) overcoat comprising a neutral copolymer of polymethacrylic acid esters such as Eudragit E30D containing metallic stearates wherein the Eudragit E30D is present to the extent of 5% to 12% by weight of the uncoated spheroids and the metallic stearate is present to the extent of 9% to 16% by weight of the Eudragit E30D solids and preferably about 12.5% by weight of the Eudragit E30D solids.
A separate and distinct aspect of the present invention relates to the double coated spheroids used as the third dose of the active medicinal substance.
Suitable pharmaceutical excipients for the powder blend of the medicinal substance include lactose, microcrystalline celulose, starch, calcium phosphate, calcium sulfate, stearic acid, magnesium stearate and disintegrants.
Eudragit S is a copolymer, anionic in character, based on methacrylic acid and methacrylic acid methyl ester. The ratio of free carboxylic groups to the esters is approximately 1:2. The mean molecular weight is 135,000. Eudragit S is available as a lacquer solution in isopropyl alcohol and as a solvent free solid. It is known as methacrylic acid copolymer, Type B, N.F.
Eudragit E30D is a copolymer, neutral in character, based on polymethacrylic acid esters. The mean molecular weight is 800,000. Eudragit E 30 D is available as a 30% (28.5%-31.5%) aqueous dispersion. Both Eudragit S and Eudragit E30D are available from Rohm Pharma, D-6108 Weiterstadt 1, Dr. -Otto -Rohm-Str. 2-4, West Germany.
Metalic stearates include zinc stearate, calcium stearate and magnesium stearate.
Explotab is a trade name for sodium starch glycolate. Sodium starch glycolate is the sodium salt of a carboxymethyl ether of starch. It is available from Edward Mendell Co., Inc., Route 52, Carmel N.Y. 10512, U.S.A.
AcDiSol is a trade name for carboxymethylcellulose sodium. It is the sodium salt of a polycarboxymethyl ether of cellulose, available from FMC Corporation, 200 Market St., Philadelphia, Pa. 19103, U.S.A.
Other disintegrants such as Amberlite can be used instead of Explotab and AcDiSol.
Suitable grades of hydroxypropyl methylcellulose for use in the present invention are the Methocel brand, made by Dow Chemical Comany, Midland, Mich., U.S.A., grades E, F and K having a viscosity range of about 3500 to about 5600 cps and preferably a viscosity of about 4000 cps.
Also suitable grades of hydroxypropyl methylcellulose are the Metolose brand, made by Shin-Etsu Chemical Co., Ltd., grades 60 SH, 65 SH and 90 SH having a viscosity range of about 3500 to about 5600 cps and preferably a viscosity of about 4000 cps.
Methocel F is a grade of hydroxypropyl methylcellulose containing about 27 to 30% methoxyl content and from about 4.0 to 7.5% hydroxypropoxyl content calculated on the dried basis. Methocel K is a grade of hydroxypropyl methylcellulose containing about 19 to 25% methoxyl content and from about 4 to 12% hydroxypropoxyl content calculated on the dried basis.
The preferred grade of hydroxypropyl methylcellulose for use in the present invention is hydroxypropyl methylcellulose USP, 2910, 4000 cps (METHOCEL E4AMP) which is a propylene glycol ether of methylcellulose containing not less than 28.0% and not more than 30.0% methoxyl content, and not less than 7.0% and not more than 12.0% hydroxypropoxyl content.
A suitable non-water swellable microcrystalline cellulose is, for example, the material sold as Avicel-PH-101 (available from FMC Corporation, American Viscose Division, Avicel Sales, Marcus Hook, Pa., U.S.A.).
The polyvinyl acetate phthalate, available from Colorcon, Inc., is the standard grade.
The spheroid coatings may further contain other pharmaceutically acceptable excipients such as binders, fillers, anti-adherents and the like.
A still further preferred aspect of the present invention relates to a therapeutic composition comprising a pharmaceutical hard gelatin capsule containing three groups of spheroids containing an active medicinal substance, wherein (a) the first group of spheroids comprising uncoated spheroids contains the medicinal substance for maximum release thereof within a period of two hours after ingestion, (b) the second group of spheroids comprising coated spheroids contains the medicinal substance in a spheroid core coated with a pH sensitive coat comprising a copolymer based on methacrylic acid and methacrylic acid methyl ester or polyvinyl acetate phthalate, the coat having an effective thickness to provide a maximum release of medicinal substance in a period of 2 to 6 hours after ingestion, and (c) the third group of spheroids comprising coated spheroids contains medicinal substance in a spheroid core coated with an undercoat of hydroxypropyl methylcellulose and an overcoat of a neutral copolymer based on polymethacrylic acid esters containing metallic stearates, the coats having an effective thickness to provide a maximum release of medicinal substance 4 to 10 hours after ingestion.
The following examples are by way of illustration of the preferred embodiments of the therapeutic preparation of the present invention and its manner of preparation.
In the first four of these examples, the uncoated spheroids were made in accordance with the teachings of U.S. Pat. No. 4,138,475 in the following manner:
Propanolol hydrochloride (60 kg.) and microcrystalline cellulose (Avicel-PH-101; 40 kg.) were blended together in a 450 liter planetary mixer. Water (50 kg.) was added, and the mixer was run for 10 minutes until a homogeneous, plastic mass was obtained. The mass was extruded under pressure through a perforated cylinder to give cylindrical extrudates of nominally 1 mm. diameter.
The damp extrudates (in batches of 15 to 20 kg.) were placed in a spheronizer in which the rotating disc (diameter 68 cm.) rotated at 300 to 400 r.p.m. The rotation was continued for 10 minutes, and the resulting spheroids were then dried at 60.degree. C. in a fluidized bed drier. The dried spheroids were passed over a 1.4 mm. screen, and those which passed through were subjected to a 0.7 mm. screen. The over-and under-sized spheroids were discarded.